单项选择题
Many diesel engine exhaust valves are being constructed with hollow stems filled with sodium in order to （）
A.provide added wear protection against today’s corrosive quality of fuel
B.increase overall valve strength due to the high gas pressures
C.assist in dissipating heat due to the extreme operating temperatures
D.reduce the overall weight of the valve thus helping eliminate valve spring surge and hammering
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相关考题
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单项选择题
Cracking of a diesel piston crown can result from（）
A.Excessive piston to liner clearance
B.The underside of the piston crown being excessively dirty lowering the rate of heat transfer
C.Faulty nozzle spray
D.All of the above -
单项选择题
In an auxiliary diesel engine, the reason for knurling the piston skirt is to（）
A.improve skirt lubrication
B.allow for expansion
C.transmit forces evenly
D.improve the piston seal -
单项选择题
Which of the listed design features is found in an exhaust valve and NOT in an intake valve?（）
A.Hard alloy steel construction
B.Beveled edges on the valve head
C.Low alloy steel construction
D.Poppet type design
